This invention relates to a drive transmission and more particularly to a clutch and braking arrangement for chain saws.
The applicant's copending application Ser. No. 35,683, filed May 3, 1979, and entitled Clutch-Brake Mechanism describes a clutch and braking arrangement for chain saws. In the structure described in that application, a relatively high energizing force is desirably imposed on the clutch shoes in operation. However, in the event the load on the clutch becomes excessive, as for example when the saw chain becomes stuck in its kerf, the consequent clutch slippage generates a substantial heat and subjects the parts to inordinate wear to adversely affect the life of the clutch parts. It is generally an object of this invention to provide a transmission wherein a relatively high energizing force can be imposed on the drive clutch but its slippage due to excessive load is generally precluded to avoid abusive heat and wear thereon and thus provide for a longer life transmission.